whereis isn't portable - switch to which

`whereis` provides different results on different OS's.  Changed to use which

See:

```
jdonat > JesseDonat-MBP ~ » /usr/bin/whereis php node mysql vim python ruby java apache2 nginx openssl vsftpd make                                                 1↵ 15:58:57
/usr/bin/php
/usr/bin/vim
/usr/bin/python
/usr/bin/ruby
/usr/bin/java
/usr/bin/openssl
/usr/bin/make
```

vs

```
php: /usr/bin/php /etc/php.ini /etc/php.d /usr/lib64/php /usr/share/php /usr/share/man/man1/php.1.gz
node:
mysql: /usr/bin/mysql /usr/lib64/mysql /usr/include/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.gz
vim: /usr/bin/vim /usr/share/vim /usr/share/man/man1/vim.1.gz
python: /usr/bin/python2.6 /usr/bin/python2.6-config /usr/bin/python /usr/lib/python2.6 /usr/lib64/python2.6 /usr/local/bin/python2.7-config /usr/local/bin/python2.7 /usr/local/bin/python /usr/local/lib/python2.7 /usr/include/python2.6 /usr/share/man/man1/python.1.gz
ruby: /usr/lib/ruby /usr/lib64/ruby /usr/local/bin/ruby /usr/local/lib/ruby
java: /usr/bin/java /etc/java /usr/lib/java /usr/share/java /usr/share/man/man1/java.1.gz
apache2:
nginx:
openssl: /usr/bin/openssl /usr/lib64/openssl /usr/include/openssl /usr/share/man/man1/openssl.1ssl.gz
vsftpd:
make: /usr/bin/make /usr/share/man/man1/make.1.gz /usr/share/man/man1p/make.1p.gz
```